The present invention relates to switch mechanisms, and multidirectional operation switches and multidirectional operation units employing switch mechanisms. These are mainly used for input panels of mobile communications equipment such as mobile phones and pagers, and small and multifunctional electronic apparatuses such as remote controls, audio equipment, games machines, car navigation systems, and digital cameras.
A multidirectional operation switch employing a conventional switch mechanism is described next with reference to FIGS. 10 to 13.
FIG. 10 is a front section view of a conventional multidirectional operation switch.
FIG. 11 is an exploded perspective of the same switch. In the multidirectional operation switch in FIGS. 10 and 11, box case 31 made of insulating resin has a cavity at its center. The open top of this cavity is covered with cover 32, typically made of a metal sheet.
FIG. 12 is a plan view of box case 31.
As shown in FIG. 12, common fixed contact 53 and eight inner fixed contacts 33 to 40 are fixed on the bottom face of the cavity of box case 31, typically by insert molding.
The rim of dome-shaped flexible contact 41 made of a thin resilient metal sheet is placed on common fixed contact 53. All eight inner fixed contacts 33 to 40 are disposed inside common fixed contact 53 on a circumference centering on the center of box case 31 at equal intervals.
These fixed contacts 53 and 33 to 40 are electrically coupled to lead-out terminals 63 and 43 to 50 disposed on the outer face of box case 31.
The above common fixed contact 53 is a contact used commonly for electrical coupling with other inner fixed contacts 33 to 40 (hereafter referred to as a common contact). A lead-out terminal electrically coupled to fixed contact 53 is called common terminal 63.
The cavity of box case 31 is octagonal when seen from the top, and its inner wall has eight corners 31A.
Operating member 42 has shaft 42B and octagonal flange 42A at the bottom of shaft 42B. Flange 42 is made integrally with shaft 42B. Operating member 42 is placed such that shaft 42B protrudes upward from through hole 32A at the center of cover 32, and flange 42A is housed inside the cavity of box case 31. Operating member 42 is thus placed inside box case 31, allowing a tilting operation, but restricting the rotation by inner wall corners 31A.
On the bottom face of flange 42A of operating member 42, eight pushing elements 42D, in total, are provided at positions corresponding to inner fixed contacts 33 to 40 on the bottom face of box case 31.
Dome-shaped flexible contact 41 is positioned by a circular bottom area formed by the inner wall of box case 31 such that its center and the center of operating member 42 match, and placed on common contact 53.
Pushing element 42D contacts the top face of this dome-shaped flexible contact 41. This makes the top face of flange 42A of operating member 42 resiliently contact the bottom face of cover 32 so that operating member 42 is maintained in a vertical neutral position.
Next, the operation of the conventional multidirectional operation switch as configured above is described.
First, in the normal state, as shown in FIG. 10, connection between any pair of the contacts is in the OFF state
FIG. 13 is a front sectional view of operating member 42 during tilting operation.
Key 52 is mounted on top end 42C of shaft 42B of operating member 42. When the left top face of key 52 is pressed, as shown by arrow 212 in FIG. 13, operating member 42 tilts about a fulcrum at the right top face of flange 42A.
Pushing element 42D on the bottom face corresponding to the tilting direction of operating member 42 then pushes dome-shaped flexible contact 41 and partially inverts dome-shaped flexible contact 41. Then, dome-shaped flexible contact 41 provides tactile xe2x80x98clickxe2x80x99 and contacts inner fixed contact 34 at the left bottom of box case 31 to turn ON between common contact 53 and inner fixed common contacts 34. Here, only lead-out common terminal 63 and terminal 44 are electrically coupled.
When the pushing force applied to key 52 is released, pushing element 42D on the bottom face of operating member 42 is pushed back due to the resilience of dome-shaped flexible contact 41, and operating member 42 returns to the vertical neutral position.
In the same way, common terminal 63 and one of the lead-out terminals 43 to 50 corresponding to each pushing position are electrically coupled when a different part of key 52 is pushed.
The above multidirectional operation switch with the conventional switch mechanism has terminals 43 and 50 to 63 corresponding respectively to inner fixed contacts 33 to 40 and common contact 53. Accordingly, the large numbers of terminals hinders downsizing of such multidirectional operation switches.
The present invention aims to offer a smaller switch mechanism with fewer terminals, and a multidirectional operation switch and multidirectional operation unit using this switch mechanism.
The switch mechanism of the present invention includes a flexible contact and multiple fixed contacts. The multiple fixed contacts are disposed such as to face the flexible contact, and include i) multiple first common contacts used commonly for electrical coupling; ii) multiple second common contacts used commonly for electrical coupling; and iii) multiple independent contacts which are electrically independent.
The multiple fixed contacts are disposed such that they are aligned clockwise or counterclockwise repeatedly in a group in the sequence of: first common contact, independent contact, second common contact, and independent contact. In fixed contacts, two adjacent contacts are electrically coupled when the flexible contact touches the two adjacent fixed contacts.
Since the multiple fixed contacts are disposed in the sequence as described above, the first common contacts or second common contacts and the independent contact adjacent to it are electrically coupled.
In the multidirectional operation switch of the present invention, the multiple fixed contacts are disposed on the inner bottom of the box case made of insulating resin which has an open top.
In addition, a dome-shaped flexible contact made of a thin resilient metal sheet is disposed inside the box case such as to cover the multiple fixed contacts.
A cover with a through hole covers the opening of the box case.
An operating member is configured with a shaft, flange, and pushing element which are integrally molded.
The shaft protrudes upward from the through hole. The flange is formed at the bottom end of the shaft, and its periphery is tiltably supported by an inner wall of the cavity of the case. The pushing element is disposed on the bottom face of the flange in a position respectively corresponding to the intermediate position between adjacent fixed contacts so as to contact the dome-shaped flexible contact.
The multiple fixed contacts include i) multiple first common contacts used commonly for electrical coupling; ii) multiple second common contacts used commonly for electrical coupling; and iii) multiple independent contacts which are electrically independent These multiple fixed contacts are disposed such that they are aligned clockwise or counterclockwise repeatedly in a group in the sequence of: one first common contact, one independent contact, one second common contact, and another one independent contact.
The dome-shaped flexible contact is pressed by the pushing element and contacts two adjacent fixed contacts. This makes the two adjacent fixed contacts electrically coupled. More specifically, the first common contact or second common contact and the independent contact adjacent to it are electrically coupled.
In the multidirectional operation unit of the present invention, the multiple fixed contacts are disposed on a wiring board facing the flexible contact. The multiple fixed contacts include i) multiple first common contacts used commonly for electrical coupling; ii) multiple second common contacts used commonly for electrical coupling; and iii) multiple independent contacts which are electrically independent.
These multiple fixed contacts are disposed such that they are aligned clockwise or counterclockwise repeatedly in a group in the sequence of: one first common contact, one independent contact, one second common contact, and another one independent contact. In these fixed contacts, adjacent two fixed contacts, i.e., the first common contact or second common contact and the independent contact adjacent to it, are electrically coupled when the flexible contact touches these two adjacent fixed contacts.